Atkinson/Miller multi-mode engine

[whitewiz]

Ok so here's the idea:
make an engine that changes between operating modes based on how much power is required.
Atkinson mode for high economy/low power cruising
Miller cycle mode for accelerating
use a vtec style multi lobe cam and custom ECU to switch between 2 modes
both are under-square engines with delayed intake valve closing
the miller cycle uses intake charge compression; usually a supercharger
if we want our compression to turn on/off our options are clutch or electric
we can't use a turbocharger because both engines/modes have low exhaust gas pressure

Ref: Mazda Millennia 2.3L v6 miller cycle 20cmpg 210hp
we'll scale this back to a reasonable 1L i4 @ 100hp

Ref: Toyota Prius 1.5L i4 atkinson cycle 45hmpg 76hp
our 1L i4 i'll estimate @ 55mpg

the transmission should have a high final ratio; a CVT would allow an ERS, a 6 spd manual would be harder to ERS
Lets plan on having an ERS (Energy Return System) on the transmission to store kinetic energy from braking. We'll use a giant rubber band instead of Lithium Ion batteries cuz its way cheaper.


Possible engines:
1.0L 3-cylinder ECA1 2001-2008 Insight - a rather rare engine.
2002 1.2 L L12A Honda Jazz
1999 - SZ - DOHC (by Daihatsu) 1999 - 1 L (997 cc) 1SZ Toyota Platz?
Toyota 2004 - KR - DOHC - 1.0 L (998 cc) 1KR
* Toyota Passo/Daihatsu Boon
* Toyota Aygo/Citroën C1/Peugeot 107
* Toyota Vitz/Yaris (2005–)
* Daihatsu Cuore L276 (09.2007-)
* Subaru Justy (2008-)
its undersquare, has VVT-i, aluminum block, 07-08 engine of the year.... its a winner

[basjoos]

The 1.8L i-vtec motor in the current Honda Civic does that already. It runs an atkinson cycle between 1000 and 3500rpm when at less than half load.

[whitewiz]

the Civic's power mode is otto cycle. Both the Atkinson and Miller cycle are 10-15% more efficient than the Otto cycle. I believe the Civic 1.8L produces 140hp, you'll notice the Mazda Millennia miller cycle produces almost 100hp / Liter. That would allow the proposed engine to be smaller & lighter.

[wwest40]

I wanted to say thanks for the references and clarifying things but then I saw the "tongue in cheek" rubber band reference.

The other choice for SuperCharger is to use a modern day implementation of the system Studebaker used back in the mid-fifties, a variable ratio V-drive "CVT". Drive the SuperCharger from the engine but via an e/CVT differential. An AC synchonous motor driving the opposite end of the differential with the differential output driving the SC.

That way the positive displacement SC boost could be varied independent of ICE RPMs and therefore used in place of a throttle plate to provide whatever level of intake airflow was required of the moment. Slight/low intake flow for idle and then all the way up to FULL boost at WOT, NEVER OVERBOOST.

[whitewiz]

a variable ratio V-drive "CVT"; in Canada we call that a snowmobile trany
I like the idea of a variable output charge compressor, and a CVT is possible, but i can't say as i understand what the Studebaker setup is.

Honestly I think the easiest way to test my thoery that Miller cycle and Atkinson cycle are nearly the same engine is going to be to stick a dairy blower on the front of a Prius engine and see if it produces 140hp.

Where can I find a cheap Prius with dead batteries and a giant rubber band?